the audience wants something in the story, which is directly connected to the Main Character, to begin
Start means something different in a story where the Main Character has a Resolve of Change than in a story where the Main Character has a Resolve of Steadfast. If the Main Character must Change because he lacks an essential trait, then he must Start doing or being something they currently are not. If the Main Character is holding out Steadfastly until something begins in his environment, then he is waiting for something to Start. The term simply describes an aspect of the growth which happens in the Main Character.